Zoalene (chemical name is called 3,5-dinitro-2-methylbenzoic acid) is a fairly ideal drug which is characterized of broad spectrum, efficacy, low toxicity, stable performances, small drug resistance, no residue and no influence on immunity of poultry. The product can promote the growth of chooks, if used in feeds, and it is effective against all eimeria tenella, such as eimeria tenella, eimeria necatrix, eimeria brunetti, eimeria acervulina and eimeria maxima, and effective against coccidium of turkeys, particularly against the eimeria tenella and the eimeria necatrix. The action mechanism of Zoalene is mainly to inhibit fission gemmas without sexual cycles and mainly acted on sporozoites and the first generation of agamonts. The product is not only used for prevention, but also used for treating; the applied curative dose does not have harmful effect on growth and development of the chooks and hatching rate of eggs, and have effects in good prevention on coccidiosis of rabbits; therefore, Zoalene is a good anti-considiosis medicament.
In traditional Zoalene producing methods, ortho-toluic acid is mainly adopted as a starting material, and three synthetic routes are usually used; the first route comprises the steps of nitrating the ortho-toluic acid to obtain the 3,5-dinitro-2-methylbenzoic acid, chloridizing the 3,5-dinitro-2-methylbenzoic acid to obtain acyl chloride, and carry out aminolysis action to obtain Zoalene; the second route comprises the steps of making the ortho-toluic acid into the ortho-methyl benzamide and nitrating ortho-methyl benzamide to obtain Zoalene; and the third route comprises the step of carrying out aminolysis action to obtain Zoalene. At present, the first route is the main preparation method of Zoalene because of high product yield, but in the method, a large amount of concentrated sulfuric acid and concentrated nitric acid are needed in the nitration reaction; after reacted, a large amount of waste acid is produced, and the waste acid has large acid content and sulfuric acid. The traditional waste acid treating method mainly adopts neutralization reaction, but a large amount of lime and alkali in are needed in the neutralization reaction, and costs for solid sedimentation treatment of the neutralizing product such as calcium sulfate are increased. If the waste acid is directly discharged to environment, water or soil will be acidized and ecological environment will be damaged. Therefore, if a recycling process and device can be designed for recycling the waste acid produced in the nitration reaction of the ortho-toluic acid and reusing in the reaction, the wastewater treating costs of the production process can be reduced, environment pollution can be greatly reduced, which is significant in protecting environment against pollution.
Invention Content
To solve the problem that a large amount of waste acid produced in the nitration reaction during the process of producing Zoalene pollutes the environment, the invention provides a process for recycling the waste acid produced in the process of producing the Zoalene; in the method, the concentrated sulfuric acid with a few organics is separated from water by treating the waste acid, and the recycled concentrated sulfuric acid is reused in the production process, so that the environment pollution is reduced and costs are saved; the water is applied to the production process, so that the water resources can be recycled.
On the other hand, the invention provides a device for recycling the waste acid produced in the process of producing Zoalene to realize the recycling process.
The technical scheme used in the invention is as follows: a process for recycling waste acid produced in the process of producing Zoalene, comprising a nitration process, a chlorination process and an ammonization process, wherein the nitration process comprises the following steps: putting concentrated sulfuric acid into an enamel reactor, starting a mixer, putting in ortho-toluic acid and mixing it until completely dissolved, adding nitric acid to the system, controlling the system temperature at 90-100 DEG. C., continuously mixing to react for 0.5-1.5 h after added, and then cooling; diluting the liquid with distilled water, then filtering, and then washing and drying the solid to obtain a nitration product 3,5-dinitro-2-methylbenzoic acid; putting the waste acid which is diluted and washed in the nitration process into a distillation tower, later heating, depressurizing and distilling; setting the vacuum degree for depressurizing and distilling the water acid at 0.07-0.1 MPa, putting the acid liquid A obtained by distillation and concentration into a mixing tank, and adding new concentrated sulfuric acid to the mixing tank, wherein the mass ratio of the acid liquid A to the new concentrated sulfuric acid mixed above is 1-5:1; after mixing, putting the mixed sulfuric acid to a reactor to carry out a new nitration reaction; recycling and putting the distilled water A which is obtained by heating, depressurizing and distilling into a condenser for cooling, storing the cooled distilled water A in a recycled water storage tank, and putting the distilled water A to a diluting pot to dilute the 3,5-dinitro-2-methylbenzoic acid produced in the new nitration process. The recycled waste acid contains sulfuric acid, nitric acid, water and ortho-toluic acid. From a sufficient amount of experimentation, if the acid liquid A recycled after distilled is mixed with new concentrated sulfuric acid in certain proportion under different conditions, influences on the product yield and content are different, and the product yield and content obtained in the conditions of the invention are equivalent to that obtained in the production carried out with new concentrated sulfuric acid; therefore, based on guarantee of product quality in the invention, the waste acid produced in the production process can be fully used; the recycled distilled water A contain little nitric acid, so that the distilled water A can be used for diluting in the diluting pot, and the product cannot be influenced.
For the process for recycling the waste acid produced in the process of producing the Zoalene, the starting temperature to heat the waste acid is 50-120 DEG C., and the temperature to stop depressurizing and distilling the waste acid is 135-180 DEG C.
As the preferable measure in the invention, for the process for recycling the waste acid produced in the process of producing the Zoalene, the starting temperature to heat the waste acid is 90-110 DEG C., and the temperature to stop depressurizing and distilling the waste acid is 150-170 DEG C.
As the preferable measure in the invention, for the process for recycling the waste acid produced in the process of producing the Zoalene, the waste acid A and the new concentrated sulfuric acid are mixed and put in proportion of 2 to 3:1 by weight.
For the process for recycling the waste acid produced in the process of producing the Zoalene, the input rate of the added ortho-toluic acid:nitric acid:concentrated sulfuric acid is set as 1:2-3:5-18.
For the process for recycling the waste acid produced in the process of producing the Zoalene, the input rate of the added ortho-toluic acid:nitric acid:concentrated sulfuric acid is set as 1:2.2-2.6:8-12.
For the process for recycling the waste acid produced in the process of producing the Zoalene, the dropping time of the nitric acid is 0.5-2 h.
The invention further provides a device for recycling the waste acid produced in the process of producing the Zoalene, comprising an enamel reactor, wherein a mixer is arranged in the enamel reactor, the enamel reactor is provided with a nitric acid inlet, a sulfuric acid inlet and an ortho-toluic acid inlet, wherein the outlet of the enamel reactor is connected with a diluting pot, and the diluting pot is connected with a filtering slot; the waste acid outlet is connected with the distillation tower, the distillation tower is connected with a vacuum pump, the acid liquid A outlet of the distillation tower is connected with an acid liquid A storage tank, the acid liquid A storage tank is connected with the inlet of a blending tank, the blending tank is further connected with a concentrated sulfuric acid storage tank, the outlet of the blending tank is connected with the sulfuric acid inlet of the enamel reactor, the distilled water outlet of the distillation tower is connected with a condenser, the outlet of the condenser is connected with a recycled water storage tank, and the outlet of the recycled water storage tank is connected with the diluting pot.
As the further improving measure in the invention, for the device, a metering pump I is arranged between a nitric acid storage tank and the enamel reactor, a metering pump II is arranged between the concentrated sulfuric acid storage tank and the blending tank, and a metering pump III is arranged between the acid liquid A storage tank and the blending tank.
Compared with prior art, the invention mainly has the following beneficial effects: by recycling the waste acid produced in the process of producing Zoalene in a way of heating, depressurizing and concentrating the waste acid and reusing the waste acid in the nitration reaction, the waste acid is recycled, the use ratio of the concentrated sulfuric acid is improved, the discharged wastewater does not contain the waste acid while the costs are reduced, and the environmental-friendly production process without pollution is realized; by reusing the distilled water produced when the waste acid is depressurized, distilled and concentrated in the dilution process of the nitration products, the water resources are recycled, the waste of the water resources is reduced, and the discharge of waste water produced in the process of producing the Zoalene is greatly reduced, so that not only production cost is saved, but also environment pressure is reduced; the method is simple in separation process, feasible in recycling method, high in yield, simple to operate and significant of great significance to environment protection.
Description of marks on the FIGURE: 1-distillation tower, 2-nitric acid storage tank, 3-metering pump I, 4-sulfuric acid storage tank, 5-metering pump II, 6-acid liquid A storage tank, 7-metering pump III, 8-blending tank, 9-nitric acid inlet, 10-sulfuric acid inlet, 11-ortho-toluic acid inlet, 12-enamel reactor, 13-diluting pot, 14-filtering tank, 15-condenser, 16-vacuum pump, 17-recycled water storage tank, 18-mixer, 19-water storage tank.